1. Field of the Invention
The present invention relates to an air bag which is provided on a vehicle and is inflated when the vehicle crashes against something to protect the passenger and, more particularly to an air bag whose shape at inflation has been improved.
2. Discussion of the Prior Art
As shown in FIG. 7, an air bag 21 of an air bag device is rapidly inflated when a vehicle 20 crashes against something, by gas from an inflator to protect a human body 10.
As this type of air bag, a type whose shape is an inflated state is like a flat board, is widely used. In Japanese laid open utility model publication 50-34441, an air bag 1 is disclosed, both sides of the surface thereof which faces a human body projecting forward when inflated, as shown in FIG. 3 and FIG. 4. With such an air bag 1, since the human body 10 is sandwiched from left and right sides by projecting portions 1b and 1c of the air bag which has been inflated, it is possible to securely receive the human body.
The air bag of Japanese laid open utility model publication 50-34441 has a configuration wherein the left and right sides of the surface facing a human body are made of expandable cloth and, as a result, the left and right sides of the surface facing a human body are projected forward by the pressure of gas when inflated. However, when the gas selectively flows towards one side of the air bag because of a bias current occurred in the gas flow from the inflator, for example, the expandable cloth on one side (e.g., the side of 1b) is projected primarily while the expandable cloth on the other side (the side of 1b) is not projected so much and, as a result, it is not possible to receive the human body while sandwiching it from left and right sides.
Further, at the time of inflation, the center of the expandable cloth is projected forward more than the periphery of the expandable cloth is projected. As a result, when the human body 10 in front of the projecting portion 1c (or 1b), the left and right sides of the air bag form sharp peaks as shown in FIG. 4 which may strike the human body.